Muscles And Movement

Question 1

Muscle

Answer 1

Specialized for movement; facilitate motion via contraction pairs (tense vs relaxed)

Question 2

How are muscle tissue hierarchically arranged?

Answer 2

Muscle -> fascicle -> sarcolemma -> myofiber -> myofibril -> sarcomere

Question 3

Sarcomere

Answer 3

Basic unit of muscle contraction

Question 4

Thick filaments

Answer 4

Thick braid of myosin

Question 5

Thin filaments

Answer 5

Thin braid of actin

Question 6

Which line moves during muscle contraction? Z line or M line?

Answer 6

Z line

Question 7

Sliding filament theory

Answer 7

Muscles contract when sarcomere shorten; actin moves and overlaps w/ one another and myosin doesn’t move; doesn’t change lengths

Question 8

Cross bridge cycle

Answer 8

Shortens the sarcomere

1. ATP binds to myosin head
2. Myosin head changes shape and hydrolysis the ATP into ADP + phosphate
3. Myosin head binds to actin and creates a cross bridge (still w/ ADP and phosphate)
4. ADP and phosphate group is released during power stroke (moving actin/pushing thin filament)

ADP and phosphate only unbinds when there is another ATP ready to bind to myosin

Question 9

After death, the body enters rigor mortis-a state where all muscles contract and the body tensed up. What step of the cross bridge cycle must the sarcomere be in during rigor mortis?

Answer 9

Step 4 (body is dead meaning no ATP production)

Question 10

Motor units

Answer 10

Control a number of muscle fibers to contract

Question 11

How does calcium release affect cross bridge cycle?

Answer 11

Action potentials from motor neurons open voltage gated Ca channels in the sarcoplasmic reticulum. The SR releases Ca and the Ca binds to troponin on the tropomyosin. This allows myosin to freely bind to actin and start the cross bridge cycle, which shortens the sarcomere and causing muscle contractions and movement.

Question 12

Troponin

Answer 12

Ca binds to it to expose myosin binding sites

Question 13

Tropomyosin

Answer 13

Stops myosin from binding to actin

Question 14

Sarcoplasmic reticulum

Answer 14

Highly modified ER for the muscle; contains a lot of Ca

Question 15

Transverse tubules

Answer 15

Extends into the cell and touches SR and transfers action potentials to open Ca channels in the SR

Question 16

Myoglobin

Answer 16

Binds to oxygen in muscles; just like hemoglobin for blood cells

Question 17

What is the difference between slow twitch fibers and fast twitch fibers?

Answer 17

Slow twitch: slow contraction, aerobic respiration, high endurance, many mitochondria, high concentration of myoglobin

Fast twitch: fast contraction, glycolysis/anaerobic respiration, low endurance, few mitochondria, low concentration of myoglobin

Question 18

Extreme slow twitch example.

Answer 18

Sloth

Question 19

Extreme fast twitch example.

Answer 19

Club winged manakin

Question 20

Locomotion

Answer 20

Requires a skeleton for muscles to push against

Question 21

Hydrostatic skeleton

Answer 21

Body cavity full of water

Question 22

Exoskeleton

Answer 22

Made of chitin and calcium

Question 23

Endoskeleton

Answer 23

Bones made of calcium and cartilage

Question 24

Examples of locomotion (swimming)

Answer 24

Jet propulsion, up and down, suction, flight, and side to side

Question 25

Examples of locomotion (terrestrial)

Answer 25

Running, leaping, crawling, flight